Generally, in the NG WD system, the full-wave fiber input power is generally less than 20dBm. What is the main reason?

What are the ways that NG WDM devices create fibers? (Multiple Choice)

In the WDM system, after a certain distance of transmission, the optical signal-to-noise ratio of the receiving signal will be reduced to a certain extent. What is the main reason?

In the WDM networking design, as long as there are enough EDFA cascades to compensate for the loss of optical power during transmission. Then the system can transmit a long distance without restriction.

In general, which of the following operations will cause a short interruption in monitoring of existing network devices? (Multiple Choice)